EP0544701B1 - Polyhydroxy acid films - Google Patents

Polyhydroxy acid films Download PDF

Info

Publication number
EP0544701B1
EP0544701B1 EP91913883A EP91913883A EP0544701B1 EP 0544701 B1 EP0544701 B1 EP 0544701B1 EP 91913883 A EP91913883 A EP 91913883A EP 91913883 A EP91913883 A EP 91913883A EP 0544701 B1 EP0544701 B1 EP 0544701B1
Authority
EP
European Patent Office
Prior art keywords
film
polymer
hydroxy
monomeric
hydroxy acids
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91913883A
Other languages
German (de)
French (fr)
Other versions
EP0544701A1 (en
EP0544701A4 (en
Inventor
Gary Lee Loomis
George Joseph Ostapchenko
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EIDP Inc
Original Assignee
EI Du Pont de Nemours and Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=24205821&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0544701(B1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Publication of EP0544701A1 publication Critical patent/EP0544701A1/en
Publication of EP0544701A4 publication Critical patent/EP0544701A4/en
Application granted granted Critical
Publication of EP0544701B1 publication Critical patent/EP0544701B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/04Oxygen-containing compounds
    • C08K5/09Carboxylic acids; Metal salts thereof; Anhydrides thereof
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/005Shaping by stretching, e.g. drawing through a die; Apparatus therefor characterised by the choice of materials
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/06Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/04Polyesters derived from hydroxycarboxylic acids, e.g. lactones
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C71/00After-treatment of articles without altering their shape; Apparatus therefor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037Other properties
    • B29K2995/0049Heat shrinkable

Definitions

  • This invention relates to certain polyhydroxy acid compositions and films produced from these compositions, which are useful as degradable packaging materials.
  • High molecular weight polymers of hydroxy acids and cyclic dimer products of esterification of alpha-hydroxy acids, particularly glycolic acid and lactic acid, are well known to be degradable, and are found useful for disposable packaging that will substantially and readily deteriorate to harmless byproducts under conditions existing in the natural environment or employed in suitable waste treatment facilities. It is desirable for packaging material to possess additional beneficial physical properties including optical clarity, tensile strength, resistance to puncture and, optionally, to be shrinkable.
  • Shrinkable films are useful for "shrink-wrap" packaging. Shrink-wrapping is the process by which a film structure placed around an object contracts upon application of convective or radiant heat, to provide a tight, protective, self-sealing container. In order to make polyhydroxy acid films shrinkable, the polyhydroxy acid films must be oriented by mechanical stretching procedures.
  • polyhydroxy acids of commercial significance contain large proportions of specific asymmetrical, carbon atoms and may be, therefore, appreciably crystalline and brittle. Such polymers are less able to withstand the demanding film-forming and orientation processes without excessive film breakage causing low yield. Further, polyhydroxy acid films possessing an appreciable crystallinity can become brittle on aging.
  • a method of making a pliable polyhydroxy acid film is to plasticize the film by incorporating large amounts of monomeric and low molecular weight oligomeric alpha-hydroxy acid species.
  • plasticized polyhydroxy acid compositions can be difficult to extrude into films because they stick to the film-making equipment, produce films of non-uniform thickness and the plasticizer often fouls the equipment.
  • plasticized polyhydroxy acid compositions by themselves, have glass transition temperatures, Tg, which are near ambient temperatures and may not be stable under storage conditions found in warm climates.
  • plasticized polyhydroxy acid compositions may not have an appropriate rate of degradation to maintain structural integrity for the intended useful life of the package, and, when subsequently oriented to shrinkable film, may not exhibit the heat set shrink force needed for successful application to the product or for good package strength.
  • Schneider discloses in U.S. Patent No. 2,703,316, the manufacture of films from lactic acid.
  • Schneider's polylactic acid from commercial lactic acid was inherently racemic and therefore the film produced therefrom would suffer from defects similar to those of highly plasticized polyhydroxy acid compositions. It is desirable to provide degradable compositions which may be processed economically, and with a high yield, into an optically clear, robust, and biaxially oriented film for commercially useful, disposable packaging applications.
  • Polyhydroxy acids refers to polymers containing at least one hydroxy acid unit selected from: [OCH(CH 3 )COOCH(CH 3 )CO] 2 wherein q is an integer which may range from 350 to 5,000.
  • suitable non-hydroxy acid comonomers include those capable of condensation polymerization with lactide or lactic acid (e.g., lactones such as epsilon-caprolactone, beta-propiolactone, alpha,alpha-dimethyl-beta-propiolactone and dodecanolactone; lactams; and amino acids).
  • lactones such as epsilon-caprolactone, beta-propiolactone, alpha,alpha-dimethyl-beta-propiolactone and dodecanolactone; lactams; and amino acids.
  • Polyhydroxy acids may be synthesized by polymerization directly from hydroxy acid precursors, or by polymerization of the cyclic monomeric or cyclic dimeric lactone of hydroxy acid precursors.
  • a polyhydroxy acid is produced from one or more lactones
  • the choice of cyclic monomeric or cyclic dimeric species as polymerization monomer will depend upon the hydroxy acid type.
  • Polymerization from cyclic lactone is preferred for producing high molecular weight polyhydroxy acids because equilibrium reactions with the intermediate, cyclic dimer and low molecular weight species place practical limits on the molecular weight of polymers produced directly from hydroxy acids.
  • Polyhydroxy acids of this invention have molecular weights at least high enough to provide sufficient viscosity and strength to form a sustainable film from the polymer melt.
  • Polyhydroxy acids which possess an average molecular weight ranging from about 50,000 to about 600,000; and preferably from about 150,000 to about 450,000 are effective in this invention. If the molecular weight is too high, excessive degradation occurs at the temperatures required to melt process the compositions.
  • degradation as used herein with respect to the polyhydroxy acids means that the polyhydroxy acid portion of the degradable material is biodegradable and, more importantly, degradable by hydrolysis.
  • the degradation rate is consistent with its intended usage (e.g., the product does not degrade significantly in normal storage and usage, but will degrade in a reasonable time, after discarding).
  • slightly acidic or basic conditions may be used advantageously.
  • the rate of hydrolysis degradation is affected by the degree of polymer crystallinity and amount of water exposure.
  • monomer units can be recovered if desired for reconversion to useful polyhydroxy acid, or the monomer units can be discarded as an environmentally benign waste material.
  • “Hazy” products generally outside the scope of this invention, have impaired transparency caused by the exuding of low molecular weight plasticizer to the surfaces of the films or high crystalline content of the starting polymer.
  • ambient temperature refers to the highest temperature at which the film product will be exposed during use or storage. Normally, this will range from room temperature (28°C) or below when under refrigeration, up to 40°C or more when in warehouse storage.
  • Preferred polyhydroxy acids of the present invention are those wherein 55-99 mol% is the major component composed of the (i) hydroxy acid units discussed above wherein R' is hydrogen and R" is the methyl radical, and having 80-97 mol% of asymmetric carbon atoms R- configuration and 3-20 mol% S-configuration or 80-97 mol% S- configuration and 3-20 mol% R- configuration; and wherein 1-45 mol% is the minor component composed of either an (i) hydroxy acid unit of such asymmetric carbon content that the total R- or S- configuration in major and minor components do not exceed 97 mol% of asymmetric carbon atoms, or any hydroxy acid units (ii) to (iv) or suitable non-hydroxy acid comonomers.
  • a preferred polyhydroxy acid may, for example, contain a major component of 65 mol% hydroxy acid unit (i) in which 90 mol% of asymmetric carbon atoms are S- configuration.
  • the minor component will be 35 mol% and might be completely composed of hydroxy acid unit (ii) or a suitable non-hydroxy acid comonomer.
  • the minor component might be additional hydroxy acid unit (i) but the fraction of asymmetric carbon atoms which are S- configuration in the minor component can be no greater than that which when added to the S- atoms of the major component, do not raise the S- atom content of the total above 97 mol%.
  • the range of R- and S- asymmetric carbon atoms in the major component of polyhydroxy acid is 85-96 mol% and the total R- and S- asymmetric carbon atoms in major and minor components does not exceed 96 mol%.
  • R- and S- refer to the standard nomenclature for identifying stereoisomer configurations of asymmetrical carbon.
  • the percentages of R- and S- carbons indicated herein refer only to fractions of asymmetrical carbon atoms in the polymer chains and not to total carbon atoms in the polymer chains.
  • Asymmetrical carbon atoms are those having no less than four different substituent radical groups attached to them.
  • compositions have narrow ranges of selected asymmetrical carbon atoms because polymers containing more equal fractions of R- and S- carbon atoms 1) demonstrate accelerated degradation by hydrolysis, and 2) produce films possessing adjacent layers which often adhere to each other that are prone to degradation during film processing.
  • films made outside these ranges may be hazy and/or brittle.
  • polymer films having fractions above the 97% S- carbon atom range are substantially crystalline after hot processing, such as in film production. Crystallinity is detrimental to film-forming capability, to the optical clarity of the films formed from crystalline polymers and to the ability to successfully orient films formed from crystalline polymers by stretching. Crystalline polymer films are also more brittle than amorphous polymer films.
  • a method for reducing the negative effects of highly crystalline polymer on film properties is to plasticize the polymer by incorporating and dispersing monomeric, low molecular weight oligomeric species within the polymer matrix.
  • Plasticizers for the polyhydroxy acids of the present invention are monomeric hydroxy acids, lactides of monomeric hydroxy acids, lactyl lactate non-cyclic dimers of monomeric hydroxy acids and other oligomers of monomeric hydroxy acids having a molecular weight of up to 450.
  • plasticizers in the polyhydroxy acids produce films of uneven thickness. Where films are made by casting onto drums, excessive plasticizer may separate from the film, stick to and foul the drum, or may cause the film to stick to the drum. Thus, it has been found necessary to use a polymer containing a minimal amount of plasticizer.
  • the amount of plasticizers needed to obtain useful films in accordance with the present invention ranges from about 0.10 to about 8 wt%, and preferably from about 0.2 to 6 wt%.
  • a highly preferable composition range is from about 0.2 to 0.4 wt% plasticizer.
  • plasticizer levels are based upon the concentrations of the polyhydroxy acid and plasticizer in the feedstock which is used to produce the film and do not necessarily correspond to the concentrations of the plasticizer in the film produced from the compositions of the present invention.
  • Plasticizer content may be determined by the lactide content analysis methods taught in the Journal of Applied Polymer Science, Kohn, Van den Berg, Van de Ridder and Feyen, volume 29, pages 4265-4277 (1984). Should it become necessary to reduce the concentration of plasticizers in a plasticizer-rich composition, a devolatilizing extruder can be used either as a separate step or during film extrusion.
  • the shrinkage value is an indicator of film shrinkage performance.
  • the shrinkage value is determined by 1) cutting a 10 cm by 10 cm square sample from an oriented film such that the edges of the sample are parallel to the machine and transverse film directions; 2) immersing the sample in boiling water for 1 minute; 3) measuring and averaging the length and width of the boiled film; 4) and calculating percent shrinkage value by subtracting the averaged boiled film length and width from 10, then multiplying the difference by 10. For example, assuming that the average length and width of a boiled film sample are 6 cm, the film shrinkage value is calculated as (10-6) times 10, or 40%.
  • Polymeric compositions of the present invention are formed into films of uniform thickness ranging from about 0.05 to 2 mm prior to orientation.
  • Film forming may be accomplished by melt extrusion and sheet casting, blow molding, precipitation from solvent or other means which are well known to produce films from polymers. Films thus formed may be fed directly to orientation equipment or wound onto pools or otherwise conveniently collected for storage and subsequent processing or use.
  • Biaxially orienting means to stretch the film along the direction in which it travels, called the machine direction (MD), and in directions 90 degrees to the machine direction in the plane of the film, known as the transverse direction (TD), thereby extending the film to at least two times the film's initial MD and TD direction dimensions.
  • Biaxial orienting of the present invention includes simultaneous MD and TD stretching and sequential stretching.
  • One method of simultaneous biaxial orienting entails blowing a tubular film while stretching the tube in the machine direction. The biaxially orientation is performed while heating and maintaining the film temperature above the polyhydroxy acid glass transition temperature and below its melting temperature.
  • the polyhydroxy acid glass transition temperature is measured by differential scanning calorimetry (DSC).
  • DSC differential scanning calorimetry
  • the glass transition temperature decreases with increasing plasticizer content and is about 60°C for a composition containing 0.28 wt% plasticizer but only 40°C for a composition containing 20 wt% plasticizer.
  • High plasticizer concentrations have been found to be unacceptable because the glass transition temperatures produced therefrom are too near temperatures expected during storage and transport in warm climate regions.
  • Biaxially oriented films can be rendered non-shrinkable by heat-setting.
  • Heat-setting is achieved by subjecting the oriented polymeric film to a temperature above the polyhydroxy acid glass transition temperature but below its melting temperature while maintaining the film under restraint.
  • the duration of heat-setting found effective is from about 1 to 120 seconds and preferably from about 1 to 80 seconds.
  • Non-shrinkable products of this invention are defined as films that will not shrink more than 5 % when immersed in boiling water for 1 minute. Non-shrinkable degradable films are useful, for example, in the production of microwave-cookable food packaging, trash bags and waste container liners.
  • the present invention is illustrated by the following representative examples of certain preferred embodiments, wherein all parts, proportions, and percentages are by weight, unless otherwise indicated. All units of weight and measure other than SI units have been converted to SI units.
  • a polyhydroxy acid composition containing greater than 85% S- and less than 15% R-asymmetrical carbon atoms and having molecular weight of about 275,000, and containing less than 0.4% plasticizer as determined by lactide content analysis, is extruded into films of about 0.03 and 0.23 mm thickness by a 28 mm Werner-Pfleiderer twin-screw extruder equipped with a devolatilization port and a 25 cm wide, vertical die having 2.5 mm die gap.
  • the films are isolated on a 25 cm diameter, chrome-plated, cooling roll maintained at 20°C. Both films are weak and brittle.
  • the 0.23 cm thickness film is biaxially oriented by stretching to three times its original width and length at 65°C using a T.M. Long Co., Inc. Film Stretcher.
  • the oriented film is strong, stiff, optically clear and glossy, and has a good shrinkable film product shrinkage value of 66 %.
  • the oriented film is placed under restraint and heat set for 1 minute at 130°C. It remains strong and flexible and has a shrinkage value of 4 % which is good for non-shrinkable film products.
  • Example 1 Prior to heat setting a sample of the biaxially oriented film of Example 1 is wrapped around a 7.6 cm wide, 12.7 cm long, 0.64 cm high pad of paper and held in place with double-sided adhesive tape. The wrapped package is placed in a hot air convection oven at 100°C for one minute. The film shrinks uniformly around the pad and is optically clear and glossy. After storage at room temperature for 15 months, no film degradation is observed, indicating its usefulness in shrink-wrap applications.
  • a polyhydroxy acid composition containing greater than 85% S-and less than 15% R-asymmetrical carbon atoms, having 20 % plasticizer as determined by lactide content analysis is extruded into film having 0.23 mm thickness by the method of Example 1.
  • the cooling roll surface becomes coated with plasticizer which decreases heat transfer efficiency of the roll causing the film to have non-uniform thickness and optically poor, i.e., having hazy patches ranging roughly in size from 15 to 40 cm 2, film surface demonstrating that the amount of plasticizer in initial polymer was too great.
  • This film is biaxially oriented by stretching to three times its original width and length at 46°C using a T.M. Long Co., Inc. Film Stretcher. An unacceptable soft hazy film that tends to shrink slowly at room temperature is produced.
  • the film is biaxially oriented by the method of Example 1 to produce an optically clear film having shrinkage value of 71 %.
  • a polyhydroxy acid composition of somewhat greater than 97% S- and less than 3% R- asymmetrical carbon atoms and having molecular weight of about 300,000 and about 6% plasticizer as determined by lactide content analysis is extruded into a 1.5 mm thick film that is hazy.
  • the film is biaxially oriented as described in Example 1 to produce a film that becomes brittle after aging 6 months at room temperature, making it unsuitable for use in many commercial packaging applications.

Description

    BACKGROUND OF THE INVENTION
  • This invention relates to certain polyhydroxy acid compositions and films produced from these compositions, which are useful as degradable packaging materials.
  • High molecular weight polymers of hydroxy acids and cyclic dimer products of esterification of alpha-hydroxy acids, particularly glycolic acid and lactic acid, are well known to be degradable, and are found useful for disposable packaging that will substantially and readily deteriorate to harmless byproducts under conditions existing in the natural environment or employed in suitable waste treatment facilities. It is desirable for packaging material to possess additional beneficial physical properties including optical clarity, tensile strength, resistance to puncture and, optionally, to be shrinkable. Shrinkable films are useful for "shrink-wrap" packaging. Shrink-wrapping is the process by which a film structure placed around an object contracts upon application of convective or radiant heat, to provide a tight, protective, self-sealing container. In order to make polyhydroxy acid films shrinkable, the polyhydroxy acid films must be oriented by mechanical stretching procedures.
  • Many high molecular weight polyhydroxy acids of commercial significance contain large proportions of specific asymmetrical, carbon atoms and may be, therefore, appreciably crystalline and brittle. Such polymers are less able to withstand the demanding film-forming and orientation processes without excessive film breakage causing low yield. Further, polyhydroxy acid films possessing an appreciable crystallinity can become brittle on aging.
  • A method of making a pliable polyhydroxy acid film is to plasticize the film by incorporating large amounts of monomeric and low molecular weight oligomeric alpha-hydroxy acid species. However, such plasticized polyhydroxy acid compositions can be difficult to extrude into films because they stick to the film-making equipment, produce films of non-uniform thickness and the plasticizer often fouls the equipment. When successfully processed to film form, plasticized polyhydroxy acid compositions, by themselves, have glass transition temperatures, Tg, which are near ambient temperatures and may not be stable under storage conditions found in warm climates. In addition, plasticized polyhydroxy acid compositions may not have an appropriate rate of degradation to maintain structural integrity for the intended useful life of the package, and, when subsequently oriented to shrinkable film, may not exhibit the heat set shrink force needed for successful application to the product or for good package strength.
  • Schneider, discloses in U.S. Patent No. 2,703,316, the manufacture of films from lactic acid. Schneider's polylactic acid from commercial lactic acid was inherently racemic and therefore the film produced therefrom would suffer from defects similar to those of highly plasticized polyhydroxy acid compositions. It is desirable to provide degradable compositions which may be processed economically, and with a high yield, into an optically clear, robust, and biaxially oriented film for commercially useful, disposable packaging applications.
  • SUMMARY OF THE INVENTION
  • According to the present invention, there is now provided a process for making degradable, shrinkable polymer films comprising:
  • (a) melt processing the polymeric materials while subjecting the melt to sufficient mechanical agitation to obtain a uniform composition comprising:
  • (I) from 92 to 99.9 wt% polyhydroxy acid polymer containing hydroxy acid units selected from: [OCH(CH3)COOCH(CH3)CO]2 and copolymers thereof with hydroxy and non-hydroxy acid comonomers;
    wherein q is an integer from 350 to 5,000;
    and from 0.10 to 8 wt% plasticizers comprising monomeric hydroxy acids, cyclic dimers of monomeric hydroxy acids, non-cyclic dimers of monomeric hydroxy acids and other oligomers of monomeric hydroxy acids up to molecular weight of 450;
  • (b) forming the composition into a film, of uniform thickness from 0.05 to 2 mm;
  • (c) biaxially orienting the film thus produced by stretching the film to greater than two times the initial machine direction and transverse direction dimensions of the film, wherein the orienting is conducted at a temperature above the polyhydroxy acid glass transition temperature and below the melting temperature of the composition.
  • There is also provided a process for making degradable, non-shrinkable polymer films having shrinkage values less than 5% at 100°C.
  • There are further provided articles made by the foregoing processes.
  • DETAILED DESCRIPTION OF THE INVENTION
  • Degradability of the films produced by this invention is achieved by use of polyhydroxy acids. "Polyhydroxy acids" as used herein refers to polymers containing at least one hydroxy acid unit selected from: [OCH(CH3)COOCH(CH3)CO]2 wherein q is an integer which may range from 350 to 5,000.
  • Examples of suitable non-hydroxy acid comonomers include those capable of condensation polymerization with lactide or lactic acid (e.g., lactones such as epsilon-caprolactone, beta-propiolactone, alpha,alpha-dimethyl-beta-propiolactone and dodecanolactone; lactams; and amino acids). For a more complete list refer to U.S. Patent No. 4,800,219, at column 9, line 27. The values of p, q, r and s are selected to impart the degree of crystallinity and rate of crystallization which is appropriate for oriented film production.
  • Polyhydroxy acids may be synthesized by polymerization directly from hydroxy acid precursors, or by polymerization of the cyclic monomeric or cyclic dimeric lactone of hydroxy acid precursors. When a polyhydroxy acid is produced from one or more lactones, the choice of cyclic monomeric or cyclic dimeric species as polymerization monomer will depend upon the hydroxy acid type. Polymerization from cyclic lactone is preferred for producing high molecular weight polyhydroxy acids because equilibrium reactions with the intermediate, cyclic dimer and low molecular weight species place practical limits on the molecular weight of polymers produced directly from hydroxy acids.
  • Polyhydroxy acids of this invention have molecular weights at least high enough to provide sufficient viscosity and strength to form a sustainable film from the polymer melt. Polyhydroxy acids which possess an average molecular weight ranging from about 50,000 to about 600,000; and preferably from about 150,000 to about 450,000 are effective in this invention. If the molecular weight is too high, excessive degradation occurs at the temperatures required to melt process the compositions.
  • The term "degradable" as used herein with respect to the polyhydroxy acids means that the polyhydroxy acid portion of the degradable material is biodegradable and, more importantly, degradable by hydrolysis. The degradation rate is consistent with its intended usage (e.g., the product does not degrade significantly in normal storage and usage, but will degrade in a reasonable time, after discarding). For hydrolysis degradation, slightly acidic or basic conditions may be used advantageously. The rate of hydrolysis degradation is affected by the degree of polymer crystallinity and amount of water exposure. As a result of hydrolysis degradation, monomer units can be recovered if desired for reconversion to useful polyhydroxy acid, or the monomer units can be discarded as an environmentally benign waste material.
  • "Hazy" products, generally outside the scope of this invention, have impaired transparency caused by the exuding of low molecular weight plasticizer to the surfaces of the films or high crystalline content of the starting polymer.
  • The term "ambient temperature" refers to the highest temperature at which the film product will be exposed during use or storage. Normally, this will range from room temperature (28°C) or below when under refrigeration, up to 40°C or more when in warehouse storage.
  • Preferred polyhydroxy acids of the present invention are those wherein 55-99 mol% is the major component composed of the (i) hydroxy acid units discussed above wherein R' is hydrogen and R" is the methyl radical, and having 80-97 mol% of asymmetric carbon atoms R- configuration and 3-20 mol% S-configuration or 80-97 mol% S- configuration and 3-20 mol% R- configuration; and wherein 1-45 mol% is the minor component composed of either an (i) hydroxy acid unit of such asymmetric carbon content that the total R- or S- configuration in major and minor components do not exceed 97 mol% of asymmetric carbon atoms, or any hydroxy acid units (ii) to (iv) or suitable non-hydroxy acid comonomers.
  • A preferred polyhydroxy acid may, for example, contain a major component of 65 mol% hydroxy acid unit (i) in which 90 mol% of asymmetric carbon atoms are S- configuration. In this example, the minor component will be 35 mol% and might be completely composed of hydroxy acid unit (ii) or a suitable non-hydroxy acid comonomer. In this same example, the minor component might be additional hydroxy acid unit (i) but the fraction of asymmetric carbon atoms which are S- configuration in the minor component can be no greater than that which when added to the S- atoms of the major component, do not raise the S- atom content of the total above 97 mol%.
  • In more preferred embodiments of the present invention, the range of R- and S- asymmetric carbon atoms in the major component of polyhydroxy acid is 85-96 mol% and the total R- and S- asymmetric carbon atoms in major and minor components does not exceed 96 mol%.
  • The terms "R-" and "S-" refer to the standard nomenclature for identifying stereoisomer configurations of asymmetrical carbon. The percentages of R- and S- carbons indicated herein refer only to fractions of asymmetrical carbon atoms in the polymer chains and not to total carbon atoms in the polymer chains. Asymmetrical carbon atoms are those having no less than four different substituent radical groups attached to them.
  • The preferred compositions have narrow ranges of selected asymmetrical carbon atoms because polymers containing more equal fractions of R- and S- carbon atoms 1) demonstrate accelerated degradation by hydrolysis, and 2) produce films possessing adjacent layers which often adhere to each other that are prone to degradation during film processing.
  • Also, films made outside these ranges may be hazy and/or brittle. For example polymer films having fractions above the 97% S- carbon atom range are substantially crystalline after hot processing, such as in film production. Crystallinity is detrimental to film-forming capability, to the optical clarity of the films formed from crystalline polymers and to the ability to successfully orient films formed from crystalline polymers by stretching. Crystalline polymer films are also more brittle than amorphous polymer films. A method for reducing the negative effects of highly crystalline polymer on film properties is to plasticize the polymer by incorporating and dispersing monomeric, low molecular weight oligomeric species within the polymer matrix. Plasticizers for the polyhydroxy acids of the present invention are monomeric hydroxy acids, lactides of monomeric hydroxy acids, lactyl lactate non-cyclic dimers of monomeric hydroxy acids and other oligomers of monomeric hydroxy acids having a molecular weight of up to 450.
  • It has been found that an excessive concentration of plasticizers in the polyhydroxy acids produces films of uneven thickness. Where films are made by casting onto drums, excessive plasticizer may separate from the film, stick to and foul the drum, or may cause the film to stick to the drum. Thus, it has been found necessary to use a polymer containing a minimal amount of plasticizer. The amount of plasticizers needed to obtain useful films in accordance with the present invention ranges from about 0.10 to about 8 wt%, and preferably from about 0.2 to 6 wt%. A highly preferable composition range is from about 0.2 to 0.4 wt% plasticizer. These plasticizer levels are based upon the concentrations of the polyhydroxy acid and plasticizer in the feedstock which is used to produce the film and do not necessarily correspond to the concentrations of the plasticizer in the film produced from the compositions of the present invention. Plasticizer content may be determined by the lactide content analysis methods taught in the Journal of Applied Polymer Science, Kohn, Van den Berg, Van de Ridder and Feyen, volume 29, pages 4265-4277 (1984). Should it become necessary to reduce the concentration of plasticizers in a plasticizer-rich composition, a devolatilizing extruder can be used either as a separate step or during film extrusion.
  • The shrinkage value is an indicator of film shrinkage performance. The shrinkage value is determined by 1) cutting a 10 cm by 10 cm square sample from an oriented film such that the edges of the sample are parallel to the machine and transverse film directions; 2) immersing the sample in boiling water for 1 minute; 3) measuring and averaging the length and width of the boiled film; 4) and calculating percent shrinkage value by subtracting the averaged boiled film length and width from 10, then multiplying the difference by 10. For example, assuming that the average length and width of a boiled film sample are 6 cm, the film shrinkage value is calculated as (10-6) times 10, or 40%.
  • Polymeric compositions of the present invention are formed into films of uniform thickness ranging from about 0.05 to 2 mm prior to orientation. Film forming may be accomplished by melt extrusion and sheet casting, blow molding, precipitation from solvent or other means which are well known to produce films from polymers. Films thus formed may be fed directly to orientation equipment or wound onto pools or otherwise conveniently collected for storage and subsequent processing or use.
  • Polymeric films useful in shrink-wrap packaging applications may be prepared by biaxially orienting the previously discussed polyhydroxy acid composition films. Biaxially orienting means to stretch the film along the direction in which it travels, called the machine direction (MD), and in directions 90 degrees to the machine direction in the plane of the film, known as the transverse direction (TD), thereby extending the film to at least two times the film's initial MD and TD direction dimensions. Biaxial orienting of the present invention includes simultaneous MD and TD stretching and sequential stretching. One method of simultaneous biaxial orienting entails blowing a tubular film while stretching the tube in the machine direction. The biaxially orientation is performed while heating and maintaining the film temperature above the polyhydroxy acid glass transition temperature and below its melting temperature. The polyhydroxy acid glass transition temperature is measured by differential scanning calorimetry (DSC). The glass transition temperature decreases with increasing plasticizer content and is about 60°C for a composition containing 0.28 wt% plasticizer but only 40°C for a composition containing 20 wt% plasticizer. High plasticizer concentrations have been found to be unacceptable because the glass transition temperatures produced therefrom are too near temperatures expected during storage and transport in warm climate regions.
  • Biaxially oriented films can be rendered non-shrinkable by heat-setting. Heat-setting is achieved by subjecting the oriented polymeric film to a temperature above the polyhydroxy acid glass transition temperature but below its melting temperature while maintaining the film under restraint. The duration of heat-setting found effective is from about 1 to 120 seconds and preferably from about 1 to 80 seconds. "Non-shrinkable" products of this invention are defined as films that will not shrink more than 5 % when immersed in boiling water for 1 minute. Non-shrinkable degradable films are useful, for example, in the production of microwave-cookable food packaging, trash bags and waste container liners.
  • EXAMPLES
  • The present invention is illustrated by the following representative examples of certain preferred embodiments, wherein all parts, proportions, and percentages are by weight, unless otherwise indicated. All units of weight and measure other than SI units have been converted to SI units.
  • EXAMPLE 1
  • A polyhydroxy acid composition containing greater than 85% S- and less than 15% R-asymmetrical carbon atoms and having molecular weight of about 275,000, and containing less than 0.4% plasticizer as determined by lactide content analysis, is extruded into films of about 0.03 and 0.23 mm thickness by a 28 mm Werner-Pfleiderer twin-screw extruder equipped with a devolatilization port and a 25 cm wide, vertical die having 2.5 mm die gap. The films are isolated on a 25 cm diameter, chrome-plated, cooling roll maintained at 20°C. Both films are weak and brittle.
  • The 0.23 cm thickness film is biaxially oriented by stretching to three times its original width and length at 65°C using a T.M. Long Co., Inc. Film Stretcher. The oriented film is strong, stiff, optically clear and glossy, and has a good shrinkable film product shrinkage value of 66 %. The oriented film is placed under restraint and heat set for 1 minute at 130°C. It remains strong and flexible and has a shrinkage value of 4 % which is good for non-shrinkable film products.
  • EXAMPLE 2
  • Prior to heat setting a sample of the biaxially oriented film of Example 1 is wrapped around a 7.6 cm wide, 12.7 cm long, 0.64 cm high pad of paper and held in place with double-sided adhesive tape. The wrapped package is placed in a hot air convection oven at 100°C for one minute. The film shrinks uniformly around the pad and is optically clear and glossy. After storage at room temperature for 15 months, no film degradation is observed, indicating its usefulness in shrink-wrap applications.
  • In contrast, a polyhydroxy acid composition containing greater than 85% S-and less than 15% R-asymmetrical carbon atoms, having 20 % plasticizer as determined by lactide content analysis, is extruded into film having 0.23 mm thickness by the method of Example 1. After a few minutes of operation, the cooling roll surface becomes coated with plasticizer which decreases heat transfer efficiency of the roll causing the film to have non-uniform thickness and optically poor, i.e., having hazy patches ranging roughly in size from 15 to 40 cm 2, film surface demonstrating that the amount of plasticizer in initial polymer was too great.
  • This film is biaxially oriented by stretching to three times its original width and length at 46°C using a T.M. Long Co., Inc. Film Stretcher. An unacceptable soft hazy film that tends to shrink slowly at room temperature is produced.
  • EXAMPLE 3
  • A polyhydroxy acid composition containing somewhat less than 97% S- and more than 3% R-asymmetrical carbon atoms and having molecular weight of about 250,000-300,000 and about 5% plasticizer as determined by lactide content analysis, is extruded into an optically clear, 1.5 mm thick film by the method of Example 1. The film is biaxially oriented by the method of Example 1 to produce an optically clear film having shrinkage value of 71 %. In contrast, a polyhydroxy acid composition of somewhat greater than 97% S- and less than 3% R- asymmetrical carbon atoms and having molecular weight of about 300,000 and about 6% plasticizer as determined by lactide content analysis, is extruded into a 1.5 mm thick film that is hazy. The film is biaxially oriented as described in Example 1 to produce a film that becomes brittle after aging 6 months at room temperature, making it unsuitable for use in many commercial packaging applications.

Claims (7)

  1. A process for making a self-supporting polymer film comprising:
    (a) forming a composition comprising mixing from 92 to 99.9 wt% of a polyhydroxy acid polymer of weight average molecular weight of from 50,000 to 600,000 comprising hydroxy acid units selected from: [OCH(CH3)COOCH(CH3)CO]q and copolymers thereof with hydroxy and non-hydroxy acid comonomers;
    wherein q is an integer which may range from 350 to 5,000 and from 0.10 to 8 wt% plasticizer comprising at least one plasticizer selected from monomeric hydroxy acids, cyclic dimers of monomeric hydroxy acids, non-cyclic dimers of monomeric hydroxy acids and oligomers of monomeric hydroxy acids having a molecular weight of up to 450 to form a composition;
    (b) melt processing the composition;
    (c) forming said composition into a film of uniform thickness from 0.05 to 2mm; and
    (d) biaxially orientating said film by stretching said film to at least two times the initial machine direction and transverse direction dimensions of said film, wherein the orienting is conducted at a temperature above the polyhydroxy acid glass transition temperature and below the melting temperature of the composition.
  2. A process for making a self-supporting polymer film comprising:
    (a) melt processing the polymeric materials while subjecting the melt to sufficient mechanical agitation to obtain a uniform composition comprising:
    (I) from 92 to 99.9 wt% polyhydroxy acid polymer of weight average molecular weight of from 50,000 to 600,000 containing hydroxy units selected from [OCH(CH3)COOCH(CH3)CO]q and copolymers thereof with hydroxy and non-hydroxy acid comonomers;
    wherein q is an integer, which may range from 350 to 5,000;
    and having sufficient molecular weight to produce self-supporting film,
    (II) from 0.10 to 8 wt% of plasticizer comprising at least one plasticizer selected from monomeric hydroxy acids, cyclic dimers of monomeric hydroxy acids, non-cyclic dimers of monomeric hydroxy acids and other oligomers of monomeric hydroxy acids up to molecular weight of 450;
    (b) forming the composition into a film of uniform thickness from 0.05 to 2mm;
    (c) biaxially orienting the film thus produced by stretching it to a greater than two times its initial machine direction and transverse direction dimensions at a temperature above the polyhydroxy acid glass transition temperature and below the melting temperature of the composition; and
    (d) heat-setting the biaxially oriented film thus produced by heating it to a temperature above the polymer glass transition temperature but below the polymer melt temperature while maintaining the film under restraint.
  3. A process of claim 1 or claim 2, wherein said film possesses a tensile strength of 80 MPa to 200 MPa and an elongation at break of 30 to 140%.
  4. A process of claim 3, wherein from 80 to 97 mol% of the carbon atoms in the polymer chain of said polyhydroxy acid polymer have a configuration selected from one of the R- and S- configurations and the remaining carbon atoms in the polymer chain have a configuration selected from the other of the R- and S- configurations.
  5. A process of claim 2, wherein the plasticizer is an additive in the melt processing step (a).
  6. A self-supporting polymer film comprising:
    (I) from 92 to 99.9 wt% polyhydroxy acid polymer of weight average molecular weight of from 50,000 to 600,000 comprising at least one hydroxy acid unit selected from: [OCH(CH3)COOCH(CH3)CO]q and copolymers thereof with hydroxy and non-hydroxy acid comonomers;
    wherein q is an integer which may range from 350 to 5,000; and
    (II) from 0.10 to 8 wt% of plasticizer comprising at least one plasticizer selected from monomeric hydroxy acids, cyclic dimers of monomeric hydroxy acids, non-cyclic dimers of monomeric hydroxy acids and oligomers of monomeric hydroxy acids up to molecular weight of 450; and
    wherein said film is biaxially oriented and possesses a tensile strength of 80 MPa to 200 MPa and an elongation of break of 30 to 140%.
  7. A film of claim 6, wherein from 80 to 97 mol% the carbon atoms in the polymer chain of said polyhydroxy acid polymer and copolymers thereof have a configuration selected from one of the R- and S- configurations and the remaining carbon atoms in the polymer chain have a configuration selected from the other of the R- and S- configurations such that the total R- and S- configuration in the polymer chain is no more than 97 mol%.
EP91913883A 1990-07-16 1991-06-25 Polyhydroxy acid films Expired - Lifetime EP0544701B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US552551 1990-07-16
US07/552,551 US5076983A (en) 1990-07-16 1990-07-16 Polyhydroxy acid films
PCT/US1991/004307 WO1992001548A1 (en) 1990-07-16 1991-06-25 Polyhydroxy acid films

Publications (3)

Publication Number Publication Date
EP0544701A1 EP0544701A1 (en) 1993-06-09
EP0544701A4 EP0544701A4 (en) 1993-07-14
EP0544701B1 true EP0544701B1 (en) 2002-09-11

Family

ID=24205821

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91913883A Expired - Lifetime EP0544701B1 (en) 1990-07-16 1991-06-25 Polyhydroxy acid films

Country Status (8)

Country Link
US (1) US5076983A (en)
EP (1) EP0544701B1 (en)
JP (1) JP2945758B2 (en)
AU (1) AU8289691A (en)
IE (1) IE912457A1 (en)
MX (1) MX9100213A (en)
NZ (1) NZ238942A (en)
WO (1) WO1992001548A1 (en)

Families Citing this family (77)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6027677A (en) * 1988-08-08 2000-02-22 Chronopol, Inc. Films containing poly(hydroxy acid)s
US5252642A (en) * 1989-03-01 1993-10-12 Biopak Technology, Ltd. Degradable impact modified polyactic acid
US5180765A (en) * 1988-08-08 1993-01-19 Biopak Technology, Ltd. Biodegradable packaging thermoplastics from lactides
US5216050A (en) * 1988-08-08 1993-06-01 Biopak Technology, Ltd. Blends of polyactic acid
US5424346A (en) * 1988-08-08 1995-06-13 Ecopol, Llc Biodegradable replacement of crystal polystyrene
US6323307B1 (en) 1988-08-08 2001-11-27 Cargill Dow Polymers, Llc Degradation control of environmentally degradable disposable materials
US5502158A (en) * 1988-08-08 1996-03-26 Ecopol, Llc Degradable polymer composition
US5444113A (en) * 1988-08-08 1995-08-22 Ecopol, Llc End use applications of biodegradable polymers
US5767222A (en) * 1988-08-08 1998-06-16 Chronopol, Inc. Degradable polydioxaneone-based materials
US5518907A (en) * 1989-06-07 1996-05-21 Center For Innovative Technology Cloning and expression in Escherichia coli of the Alcaligenes eutrophus H16 poly-beta-hydroxybutyrate biosynthetic pathway
US5334520A (en) * 1990-05-25 1994-08-02 Center For Innovative Technology Production of poly-beta-hydroxybutyrate in transformed escherichia coli
US5227415A (en) * 1990-04-06 1993-07-13 Director-General Of Agency Of Industrial Science And Technology Biodegradable plastic composition
EP0544097A1 (en) * 1991-10-23 1993-06-02 Boehringer Ingelheim Kg Semi-solid mixtures of oligomers and/or polymers based on lactic acid, process for their preparation and their use as resorbable implants
US5160467A (en) * 1991-12-05 1992-11-03 Joseph R. DeGeorge Method for producing biodegradable packaging material
US6326458B1 (en) 1992-01-24 2001-12-04 Cargill, Inc. Continuous process for the manufacture of lactide and lactide polymers
US5247058A (en) * 1992-01-24 1993-09-21 Cargill, Incorporated Continuous process for manufacture of lactide polymers with controlled optical purity
US5258488A (en) * 1992-01-24 1993-11-02 Cargill, Incorporated Continuous process for manufacture of lactide polymers with controlled optical purity
US6005067A (en) * 1992-01-24 1999-12-21 Cargill Incorporated Continuous process for manufacture of lactide polymers with controlled optical purity
US5247059A (en) * 1992-01-24 1993-09-21 Cargill, Incorporated Continuous process for the manufacture of a purified lactide from esters of lactic acid
US5142023A (en) * 1992-01-24 1992-08-25 Cargill, Incorporated Continuous process for manufacture of lactide polymers with controlled optical purity
JP3297068B2 (en) 1992-02-06 2002-07-02 三井化学株式会社 Shrink label film
US5281691A (en) * 1992-06-19 1994-01-25 Eastman Kodak Company Poly(3-hydroxyalkanoates)
KR100209818B1 (en) * 1992-09-04 1999-07-15 사또 아끼오 Degradable adhesive film and degradable resin composition
WO1994006866A1 (en) * 1992-09-22 1994-03-31 Biopak Technology, Ltd. Degradation control of environmentally degradable disposable materials
WO1994008090A1 (en) * 1992-10-02 1994-04-14 Cargill, Incorporated Paper having a melt-stable lactide polymer coating and process for manufacture thereof
US5338822A (en) * 1992-10-02 1994-08-16 Cargill, Incorporated Melt-stable lactide polymer composition and process for manufacture thereof
US6005068A (en) 1992-10-02 1999-12-21 Cargill Incorporated Melt-stable amorphous lactide polymer film and process for manufacture thereof
EP0615555B1 (en) * 1992-10-02 2001-03-21 Cargill, Incorporated A melt-stable lactide polymer fabric and process for manufacture thereof
GB9223350D0 (en) * 1992-11-06 1992-12-23 Ici Plc Polymer composition
GB9300554D0 (en) 1993-01-13 1993-03-03 Zeneca Ltd Film formation
US5631066A (en) * 1993-01-25 1997-05-20 Chronopol, Inc. Process for making metalized films and films produced therefrom
GB9311401D0 (en) * 1993-06-02 1993-07-21 Zeneca Ltd Polyester composition
GB9311402D0 (en) * 1993-06-02 1993-07-21 Zeneca Ltd Processing of polyesters
CA2127636C (en) * 1993-07-21 2009-10-20 Cheng-Kung Liu Plasticizers for fibers used to form surgical devices
US6005019A (en) * 1993-07-21 1999-12-21 United States Surgical Corporation Plasticizers for fibers used to form surgical devices
US5382617A (en) * 1993-08-20 1995-01-17 E. I. Du Pont De Nemours And Company Stabilization of poly(hydroxy acid)s derived from lactic or glycolic acid
AU689130B2 (en) 1993-10-15 1998-03-26 H.B. Fuller Licensing And Financing Inc. Biodegradable/compostable hot melt adhesives comprising polyester of lactic acid
GB9325952D0 (en) * 1993-12-20 1994-02-23 Zeneca Ltd Process for preparing films and coatings
JP3330712B2 (en) * 1994-01-11 2002-09-30 三菱樹脂株式会社 Method for producing polylactic acid-based film
JPH07205278A (en) * 1994-01-11 1995-08-08 Mitsubishi Plastics Ind Ltd Production of stretched film of polylactic acid polymer
JP3328418B2 (en) * 1994-03-28 2002-09-24 三菱樹脂株式会社 Heat-shrinkable polylactic acid film
US5763513A (en) * 1994-05-19 1998-06-09 Mitsui Toatsu Chemicals, Inc. L-lactic acid polymer composition, molded product and film
GB9411792D0 (en) * 1994-06-13 1994-08-03 Zeneca Ltd Polymer composition
US5472518A (en) * 1994-12-30 1995-12-05 Minnesota Mining And Manufacturing Company Method of disposal for dispersible compositions and articles
US6579814B1 (en) 1994-12-30 2003-06-17 3M Innovative Properties Company Dispersible compositions and articles of sheath-core microfibers and method of disposal for such compositions and articles
US5766748A (en) * 1995-11-30 1998-06-16 Mitsui Chemicals, Inc. Stretched film of lactic acid-based polymer
JP3330273B2 (en) * 1996-01-11 2002-09-30 三菱樹脂株式会社 Heat-shrinkable polylactic acid-based film and method for producing the same
US5756651A (en) * 1996-07-17 1998-05-26 Chronopol, Inc. Impact modified polylactide
US5952088A (en) * 1996-12-31 1999-09-14 Kimberly-Clark Worldwide, Inc. Multicomponent fiber
WO1999005207A1 (en) * 1997-07-25 1999-02-04 Monsanto Company Pha compositions and methods for their use in the production of pha films
US6025028A (en) * 1997-07-25 2000-02-15 Monsanto Company Polyhydroxyalkanoate coatings
US6089009A (en) 1997-08-28 2000-07-18 Belmont Textile Machinery Co., Inc. Fluid-jet false-twisting method and product
US6268434B1 (en) 1997-10-31 2001-07-31 Kimberly Clark Worldwide, Inc. Biodegradable polylactide nonwovens with improved fluid management properties
DE69841061D1 (en) * 1997-10-31 2009-09-24 Metabolix Inc Use of organic phosphonic or phosphinic acids, or of metal oxides or hydroxides, or of carboxylic acid salts of a metal as heat stabilizers for polyhydroxyalkanoates
US6201068B1 (en) 1997-10-31 2001-03-13 Kimberly-Clark Worldwide, Inc. Biodegradable polylactide nonwovens with improved fluid management properties
US6544455B1 (en) 1997-12-22 2003-04-08 Kimberly-Clark Worldwide, Inc. Methods for making a biodegradable thermoplastic composition
US6135987A (en) * 1997-12-22 2000-10-24 Kimberly-Clark Worldwide, Inc. Synthetic fiber
US6306782B1 (en) 1997-12-22 2001-10-23 Kimberly-Clark Worldwide, Inc. Disposable absorbent product having biodisintegratable nonwovens with improved fluid management properties
US6309988B1 (en) 1997-12-22 2001-10-30 Kimberly-Clark Worldwide, Inc. Biodisintegratable nonwovens with improved fluid management properties
US6261677B1 (en) 1997-12-22 2001-07-17 Kimberly-Clark Worldwide, Inc. Synthetic fiber
US6372850B2 (en) 1997-12-31 2002-04-16 Kimberly-Clark Worldwide, Inc. Melt processable poly (ethylene oxide) fibers
US6197860B1 (en) 1998-08-31 2001-03-06 Kimberly-Clark Worldwide, Inc. Biodegradable nonwovens with improved fluid management properties
US6194483B1 (en) 1998-08-31 2001-02-27 Kimberly-Clark Worldwide, Inc. Disposable articles having biodegradable nonwovens with improved fluid management properties
WO2001042333A2 (en) 1999-12-13 2001-06-14 Michigan State University Process for the preparation of polymers of dimeric cyclic esters
CA2440177C (en) * 2001-03-09 2011-05-24 Trespaphan Gmbh Method for producing biodegradable packaging from biaxially drawn film
EP1422044B1 (en) * 2001-07-19 2010-10-13 Toyo Seikan Kaisha, Ltd. Molded object obtained through stretching and thermal fixing and process for producing the same
US7388058B2 (en) * 2002-05-13 2008-06-17 E.I. Du Pont De Nemours And Company Polyester blend compositions and biodegradable films produced therefrom
JP2003002984A (en) * 2002-06-14 2003-01-08 Mitsubishi Plastics Ind Ltd Polylactic acid film
AU2003242475B2 (en) * 2002-06-20 2008-09-25 Toray Industries, Inc. Polylactic acid base polymer composition, molding thereof and film
NL1023720C2 (en) * 2003-06-23 2004-12-28 Univ Eindhoven Tech Method for changing the transport properties of a material, method for releasing a drug from an implant, as well as implant with drug.
US20100013121A1 (en) 2006-09-21 2010-01-21 Asahi Kasei Home Products Corporation Process for the production of polylactic acid film
US8486439B2 (en) * 2007-03-01 2013-07-16 Bioneedle Technologies Group B.V. Parenteral formulation
WO2008105662A1 (en) * 2007-03-01 2008-09-04 Bioneedle Technologies Group B.V. Biodegradable material based on opened starch
JP4972012B2 (en) * 2008-02-28 2012-07-11 株式会社クレハ Sequential biaxially stretched polyglycolic acid film, method for producing the same, and multilayer film
US8016980B2 (en) * 2008-11-25 2011-09-13 Dixie Consumer Products Llc Paper products
CN103388279A (en) * 2012-05-07 2013-11-13 滁州格美特科技有限公司 Biodegradable vegetable fiber composite film and preparation method thereof
EP2732832A3 (en) 2012-11-14 2015-07-01 Universitair Medisch Centrum Groningen (UMCG) Drug delivery device comprising an active compound and a thermo-sensitive polymeric material

Family Cites Families (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1095205A (en) * 1913-05-15 1914-05-05 Chemische Werke Vorm Dr Heinrich Byk Manufacture of lactid.
US2703316A (en) * 1951-06-05 1955-03-01 Du Pont Polymers of high melting lactide
US2668162A (en) * 1952-03-20 1954-02-02 Du Pont Preparation of high molecular weight polyhydroxyacetic ester
US3476714A (en) * 1964-04-20 1969-11-04 Du Pont Biaxially oriented polypivalolactone film
DE1642111A1 (en) * 1965-04-20 1971-12-30 Ethicon Inc Surgical sutures and process for their manufacture
NL6511211A (en) * 1965-08-27 1967-02-28
US3878284A (en) * 1971-08-12 1975-04-15 American Cyanamid Co Processes for making shaped articles such as filaments or films from solutions of polyglycolic acid
US4033938A (en) * 1974-01-21 1977-07-05 American Cyanamid Company Polymers of unsymmetrically substituted 1,4-dioxane-2,5-diones
EP0104731B1 (en) * 1982-08-27 1987-11-25 Imperial Chemical Industries Plc 3-hydroxybutyrate polymers
JPS6169431A (en) * 1984-09-14 1986-04-10 Teijin Ltd Stretching method of poly(beta-hydroxybutyric acid) molded product
US4727163A (en) * 1985-07-11 1988-02-23 E. I. Du Pont De Nemours And Company Process for preparing highly pure cyclic esters
AU603076B2 (en) * 1985-12-09 1990-11-08 W.R. Grace & Co.-Conn. Polymeric products and their manufacture
DE3708915C2 (en) * 1987-03-19 1996-04-04 Boehringer Ingelheim Kg Process for the preparation of lactide
DE3632103A1 (en) * 1986-09-20 1988-03-24 Boehringer Ingelheim Kg Process for the preparation of lactide
DE3636086A1 (en) * 1986-10-23 1988-04-28 Henkel Kgaa FATTY ACID ESTERS OF POLYGLYCERINPOLYGLYKOLETHERS, THEIR PRODUCTION AND THEIR USE
DE3778111D1 (en) * 1986-10-24 1992-05-14 Boehringer Ingelheim Kg METHOD FOR PRODUCING AND CLEANING THERMOLABILE COMPOUNDS.
DE3781133T2 (en) * 1986-12-19 1993-06-24 Akzo Nv MANUFACTURE OF POLYMILIC ACID AND COPOLYMERS THEREOF.
US4800219A (en) * 1986-12-22 1989-01-24 E. I. Du Pont De Nemours And Company Polylactide compositions
US4835293A (en) * 1987-02-24 1989-05-30 E. I. Du Pont De Nemours And Company Atmospheric pressure process for preparing pure cyclic esters
JPH02500593A (en) * 1987-06-16 1990-03-01 ベーリンガー インゲルハイム コマンディットゲゼルシャフト Meso-lactide and its manufacturing method
EP0339882A1 (en) * 1988-04-27 1989-11-02 MITSUI TOATSU CHEMICALS, Inc. Process for the production of lactide
WO1990001521A1 (en) * 1988-08-08 1990-02-22 Battelle Memorial Institute Degradable thermoplastic from lactides
BR9106821A (en) * 1990-09-06 1993-07-13 Battelle Memorial Institute PACKING THERMOPLASTICS FROM LATIC ACID

Also Published As

Publication number Publication date
EP0544701A1 (en) 1993-06-09
EP0544701A4 (en) 1993-07-14
IE912457A1 (en) 1992-01-29
AU8289691A (en) 1992-02-18
JP2945758B2 (en) 1999-09-06
JPH05508819A (en) 1993-12-09
WO1992001548A1 (en) 1992-02-06
US5076983A (en) 1991-12-31
NZ238942A (en) 1993-03-26
MX9100213A (en) 1992-02-28

Similar Documents

Publication Publication Date Title
EP0544701B1 (en) Polyhydroxy acid films
EP0548225B1 (en) Heat shrinkable films containing polyhydroxy acids
US5536807A (en) Melt-stable semi-crystalline lactide polymer film and process for manufacture thereof
US5424346A (en) Biodegradable replacement of crystal polystyrene
US6326440B1 (en) Biodegradable film and process for producing the same
EP0683207B1 (en) L-lactic acid polymer composition, molded product and film
JP4122915B2 (en) Softened polylactic acid resin stretched film and method for producing the same
KR20030096324A (en) Processing of Polyhydroxyalkanoates Using a Nucleant and a Plasticizer
JP3473714B2 (en) Heat-resistant sheet comprising lactic acid-based polymer and method for producing molded article
US6027677A (en) Films containing poly(hydroxy acid)s
KR101695926B1 (en) Polyester film and preparation method thereof
JP3670913B2 (en) Polylactic acid-based shrink film or sheet
JP3670912B2 (en) Polylactic acid-based shrink film or sheet
WO2014102544A2 (en) Packaging and labelling films
JP2006335904A (en) Polylactic acid-based oriented film
JPH11209595A (en) Method of shape-memorizing biodegradable shape-memory polymer molding product and its shape restoration
JP4245300B2 (en) Method for producing biodegradable polyester stretch molded article
JP3385086B2 (en) Biodegradable stretched polyester film and method for producing the same
JPH0977124A (en) Packing bag composed of polylactic acid polymer
JP3421620B2 (en) Document holder
JP4790920B2 (en) Stretched molded product for packaging materials
JP3663086B2 (en) Biodegradable film
JP2003245971A (en) Heat-resistant sheet formed of lactic acid polymer and method for manufacturing molded product
JP2001114352A (en) Film case
JPH10110047A (en) Biodegradable oriented film

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19930111

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): CH FR GB LI NL SE

A4 Supplementary search report drawn up and despatched

Effective date: 19930525

AK Designated contracting states

Kind code of ref document: A4

Designated state(s): CH FR GB LI NL SE

17Q First examination report despatched

Effective date: 19950410

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): CH FR GB LI NL SE

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20030612

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 20090625

Year of fee payment: 19

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20090629

Year of fee payment: 19

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20100630

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 20100624

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20100625

Year of fee payment: 20

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

EUG Se: european patent has lapsed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100630

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100630

REG Reference to a national code

Ref country code: NL

Ref legal event code: V4

Effective date: 20110625

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

Expiry date: 20110624

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20110624

Ref country code: NL

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20110625

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100626